how to get latest nginx using apt - ubuntu

I think that you must be especific with the commands:

sudo add-apt-repository ppa:nginx/stable
sudo apt-get update
sudo apt-get install nginx=0.7.67-4ppa1

Just remember to put the version of nginx from the launchpad package.

First off, make sure you follow ALL the instructions:

sudo su -
echo "deb  http://ppa.launchpad.net/nginx/stable/ubuntu lucid main" >> /etc/apt/sources.list
apt-key adv --keyserver keyserver.ubuntu.com --recv-keys C300EE8C
apt-get update 
apt-get install nginx

When you run apt-get update, do you get any errors for the nginx repository? Because the latest version in the nginx repo is 0.7.67.